1. Field of the Invention
The present invention relates to washing machines and, more particularly, to a washing machine with an inner tub designed to be linearly reciprocable along its vertical axis in addition to being rotatable on said vertical axis, thus preventing laundries from being twisted during the washing or rinsing process and improving the laundering effect of the washing machine.
2. Description of the Prior Art
FIG. 1 is a sectional view, showing the construction of a conventional washing machine with an upright washing tub.
As shown in the drawing, the conventional washing machine has an upright washing tub, concentrically suspended within a cabinet 104. This cabinet 104 forms the profile of the washing machine, and is provided with an openable cover 102 at its top end, while the washing tub comprises an outer tub 106 and a perforated rotary inner tub 108. The outer tub 106 is suspended within the cabinet 104 by a plurality of suspension arms 112, and contains water therein during the washing or rinsing process, while the perforated inner tub 108 is concentrically set within the outer tub 106, and is rotatable to wash or rinse the laundries contained therein. A drive motor 110 is installed at a position under the center of the bottom wall of the washing tub to rotate the inner tub 108 at a desired speed. The suspension arms 112 hold the outer tub 106 of the suspended washing tub within the cabinet 104, and act as a means for absorbing undesirable shocks or vibrations during the operation of the washing machine.
In the drive motor 110, a rotor 120 is integrated with a motor shaft 116, while a stator 122 surrounds the rotor 120 such that a regular gap is formed between the rotor 120 and the stator 122.
The motor shaft 116 integrally extends from the center of the rotor 120, and passes through the center of the bottom wall of the outer tub 106, with a bearing 118 set closely between the outer tub 106 and the motor shaft 116 to rotatably hold the shaft 116 relative to the outer tub 106. The upper end of the motor shaft 116, projected from the bottom wall of the outer tub 106, is fixed to the center of the bottom wall of the inner tub 108.
In the above-mentioned drive motor 110, the rotor 120 is integrated with the motor shaft 116, so that the shaft 116 holds the rotor 120 at a desired position. The stator 122 is fixedly set within a motor housing 126, which is fixed to the bottom wall of the outer tub 106.
When such a conventional washing machine is turned on, electric power is applied to the stator 122 of the drive motor 110, and so a rotating magnetic field is formed in the motor 110 by the coil wound around the stator 122, thus rotating the rotor 120 together with the motor shaft 116. The inner tub 108 of the washing tube is thus rotated relative to the outer tub 106 by the motor shaft 116, and forms active swirling currents of water within the inner tub 108 thus washing or rinsing the laundries. After a washing or rinsing process, water is discharged from the washing tub to the outside of the cabinet 104 through a drain hose. After the draining process, the washing machine typically performs a dewatering process to remove water together with detergent components from the laundries by rotating the inner tub 106 at a high speed.
However, such a conventional washing machine is problematic in that the inner tub of the washing tub is designed to only rotate on its vertical axis, and so the laundries are undesirably twisted during a washing or rinsing process. Another problem experienced in conventional washing machines with such a washing tub resides in that its rinsing and detergent dissolving performance is reduced, and so the washing machine does not accomplish the desired laundering effect.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a washing machine, of which the inner tub is designed to be linearly reciprocable along its vertical axis in addition to being rotatable on the vertical axis during a washing or rinsing process, and which thus forms vertical moving currents of water in addition to active swirling currents of water within the inner tub, thus preventing laundries from being twisted during the washing or rinsing process and which is thus improved in its overall laundering effect.
In order to accomplish the above object, the present invention provides a washing machine, comprising: a cabinet forming the profile of the washing machine, and provided with an openable cover at its top end; a washing tub suspended within the cabinet, and consisting of an outer tub suspended within the cabinet and containing water therein during the washing or rinsing process, and a perforated inner tub set within the outer tub such that the inner tub is linearly reciprocable along its vertical axis in addition to being rotatable on the vertical axis, the inner tub containing laundries therein and washing or rinsing the laundries during the washing or rinsing process; and a drive unit used for rotating and vertically reciprocating the inner tub within a predetermined stroke.